This invention relates to supplementary lighting devices, specifically electroluminescent supplementary lighting devices which have a non-planar xe2x80x9cthree-dimensionalxe2x80x9d configuration. The configuration of the present invention permits substantially the entire front face of the device to emit light.
The use of supplementary lighting devices, particularly as night lights, has been well known for a considerable period of time. Typically, supplementary lighting devices are employed so as to provide illumination in a darkened hallway, illumination in bathrooms, or in children""s and infants"" bedrooms and the like, without the necessity to turn on the primary lighting. While other purposes for the present invention may be found in aisles of public conveyances and venues such as airplanes, buses, theatres, and the like, the present discussion is particularly directed to night lights, because that is the most common embodiment.
Night lights, as their name suggests, find their usefulness when it is dark. They typically plug into an AC wall receptacle, where they will reside for a lengthy period of time. Prior art devices such as night lights are typically found in one of several categories.
One category utilizes incandescent lamp technology, which is relatively bright, and is economical to manufacture. Typically these kinds of night lights need an xe2x80x9con/offxe2x80x9d switch; often an automatic one which functions under control of a light sensing device such as a light sensitive resistor or diode. The cost of replacement of incandescent bulbs in the socket of such night lights is relatively low, as is their initial cost.
However, incandescents have several other disadvantages. For instance, they tend to have a short life with a relatively-high power consumption and a low efficiency of about 10%. Also, incandescent night lights tend to be a bright point-source light, so that their light output is relatively obtrusive. Moreover, since they generate light via heat by having a filament temperature of about 2500xc2x0 C., and since in small-format bulbs that filament is extremely close to the glass envelope, incandescent-style night-lights have dangerously hot bulb surfaces. Indeed, the inadvertent placement of such as a blanket or paper over the night light could result either in melting of the plastic housing of the night light or, worse, fire.
Another category of night light uses neon bulb technology, which has relatively low initial cost and very low power consumption, but which has a very low, typically red-coloured light and a rapid decay in their light output. Such weak light output as there is also tends to be seen as a point source, but provides little significant illumination of even the closely-adjacent area.
Fluorescent lighting devices are also used as night lights, but they tend to be expensive, requiring special circuitry to initiate their illumination and to then maintain their operation economically. They are very bright, but often too bright for many applications.
Finally, electroluminescent night lights have become popular because of several significant advantages. One advantage is that they have a broad light output area, so that they are not a point source and therefore less obtrusive. Also, they are very energy-efficient devices, so economical that they can be plugged in and essentially forgotten for their working life. Also, because of their light-generating technology they are cool to the touch. Furthermore, electroluminescent lighting devices have a reasonably long life.
A particular embodiment of night light is described hereafter with reference to a patent and design patent which defines that night light. However, for purposes of the present discussion, it can simply be stated that a typical electroluminescent night light has an appearance which is not unlike the front face of a television set in some respects, in that comprises a window which is set into a planar front face, with a significant frame around and particularly below the window. The window is set into the front face, and an electroluminescent panel resides behind that window. Typically, the electroluminescent panel has a green glow. A pair of electrical prongs extends from the back surface of the panel, in a region below the window and on the opposite facexe2x80x94the back facexe2x80x94of the night light housing.
Prior art electroluminescent night lights have some disadvantages. For instance, because they typically comprise a flat panel, their illumination is primarily directed perpendicularly from their face. The electroluminescent panel may illuminate somewhat to the sides, but it is limited illumination because the electroluminescent panel set well back behind the front face window.
Furthermore, the amount of light which can be generated through the window is not great, since they do not provide a large surface area for an electroluminescent panel, being limited by mechanical interference from the electrical blades and often by the need to restrict the size to one-half of a wall outlet. Since this restricts the window size to a fraction of the overall lamp size, their decor may not be optimal.
Another disadvantage is that despite the considerable child-safety benefit of cool electroluminescent light, there exist some additional child-safety drawbacks in the current art. Since night lights are very frequently used in nursery environments, these deficiencies are of special concern. For example, flat panel electroluminescent lighting devices may present a safety or electrical shock hazard because the electrical prongs of the device are exposed behind the device. But also, since some infants, particularly crawlers and toddlers, may well put anything they find into their mouth, there is a risk that saliva from the infant""s mouth may run down the front of the window and into the panel structure where it may contact the inner ends of the electrical prongs or the electrical wires which connect them to the opposed sides of the electroluminescent panel, causing a significant electrical shock hazard to the infant, as well as blowing a fuse or tripping a circuit interrupter.
All of the advantages, but none of the disadvantages, of prior art electroluminescent supplementary lighting devices, as discussed above, are found in electroluminescent supplementary lighting device of the present invention.
In particular, the present invention provides an electroluminescent supplementary lighting device which has a multi-planar xe2x80x9cthree-dimensional configurationxe2x80x9d, as compared to the primarily mono-planar prior art. The three-dimensional configuration gives further several advantages. They include:
Firstly, an important part of the electrical shock hazard of the prior art devices is overcome because the electroluminescent panel is completely enclosed behind a large lens piece which can be completely attached in a water-proof manner. This eliminates an important source of electrical shock hazard to infants. Also, the increased cavity area around the prongs allows special child-safety electrical-prong shields to be incorporated, which eliminates the other important source of concern.
Furthermore, electroluminescent supplementary lighting devices in keeping with the present invention are more easily adapted to provide certain international AC-blade forms which have a greater need for body depth.
In addition, electroluminescent supplementary lighting devices in keeping with the present invention have better dispersion of light in directions other than more or less perpendicular to the AC wall outlet. This is because the multi-planar front face plate emits light in many more directions.
Further, since substantially the entire front face of the present invention is light emitting. They are much more visible, and provide considerably greater illumination to the immediately surrounding area. There are also some decor advantages which evidence themselves from a fully-lit design style, since electroluminescent supplementary lighting devices, in keeping with the present invention are effectively both xe2x80x9cframelessxe2x80x9d in appearance, and also since there are various possible three-dimensional configurations, they present more opportunities to have a shape which may be more pleasing and acceptable, from an aesthetic point of view, to a broader cross-section of the population.
A plug-in electroluminescent lighting device is known from DE FRANCISCO U.S. Pat. No. 3,307,030 issued Feb. 28, 1967. This device employs a mono-planar electroluminescent element mounted on such as a glass foundation or structure, and which is put into place to serve as the cover or wall plate for a wall receptacle or wall-mounted switch. Thus, this device shows the fundamental design features of current electroluminescent nightlight designs, prior to the ready availability of flexible-plastic electroluminescent panels. Such electroluminescent devices as were depicted by De Franciso were expensive to produce, prospectively fragile when not in place, and expensive to replace.
DICKSON U.S. Pat. No. 4,138,620 issued Feb. 6, 1979 provides a multi-panel mono-planar electroluminescent panel assembly which comprises a plurality of uniformly illuminated overlapping electroluminescent panels. Their purpose is to provide a graphic advertising or signboard display which is essentially back-lit by electroluminescent panels, and which has a substantially flat structure.
TOKARZ et al. U.S. Pat. No. 4,864,473 issued Sep. 5, 1989, provides an electroluminescent dome light which is intended particularly to be placed into a convertible automobile vehicle. Its purpose is to provide a quick high light output by being mounted in a convenient place within the convertible automobile, and to take the place of a roof-mounted dome light which, of course, is not found in a convertible automobile.
MARISCHEN was granted U.S. Design patent No. DES 352,564 which issued Nov. 15, 1994 and U.S. Pat. No. 5,662,408 which issued Sep. 2, 1997, each directed to a low profile, mono-planar, electroluminescent night light. It is to the widely-used Marischen-style night lights and to others of its same general appearance and construction, that many of the above comments have been directed, as to the disadvantages thereof.
In accordance with one aspect of the present invention, there is provided an electroluminescent supplementary light device which has a multi-planar three-dimensional configuration. The device comprises an electroluminescent panel and a housing within which the electroluminescent panel is located.
The electroluminescent panel is such that its construction includes front and back electrically conductive layers with an electroluminescent phosphor layer and a dielectric layer disposed therebetween.
A housing is provided, having a substantially planar rear wall through which a pair of electrical prongs protrude for placement into mating slots of an AC power receptacle.
A translucent front face protrudes forwardly away from the substantially planar rear wall, so as to define an enclosed volume between the substantially planar rear wall and the front face.
The electrical prongs extend through the substantially planar rear wall and into the enclosed volume.
In any embodiment of the present invention, the electroluminescent panel has a predetermined shape. At least one electrical connection to each of the front and back electrically conductive layers is made.
Electrically conductive leads extend away from the electrical connection for each of the front and back electrically conductive layers, and the electrically conductive leads have sufficient length and flexibility so that they extend into the enclosed volume for electrical connection to the electrical prongs within the enclosed volume.
The translucent front face has edges which terminate at the edges of the substantially planar rear wall, and adjacent edges of the translucent front face and of the substantially planar rear wall are attached one to the other.
The electroluminescent panel is configured so that at least one side edge is placed in the region where an edge of the translucent front face is attached to an edge of the substantially planar rear wall.
The electroluminescent panel protrudes forwardly away from the at least one side edge so as to be contiguous to at least a major portion of the translucent front face.
A particular embodiment of the electroluminescent supplementary lighting device of the present invention has the translucent front face configured so as to curve forwardly from a pair of opposed side edges of the substantially planar rear wall so as to thereby define the enclosed volume so as to be forward of the substantially planar rear wall, behind the curved translucent front face and between upper and lower edges thereof.
The substantially planar rear wall has four side edges to which the translucent face can be respectively attached; and the electroluminescent panel is configured as a partial cylinder by arching a rectangular two-dimensional panel so that two opposed sides of the electroluminescent panel form an arch which corresponds to the arch of the curved translucent front face.
Another embodiment of the present invention, which is a variant of the partially cylindrical configuration, has upper and lower faces which extend rearwardly from the upper and lower edges of the curved translucent front face to the substantially planar rear wall, and the upper and lower faces each comprise an electroluminescent panel.
In a further variant of the partially cylindrical configuration, the electroluminescent supplementary lighting device of the present invention has the translucent front face configured so as to curve forwardly such that the radius of curvature of the curved shape at one of the upper and lower edges is different from the radius of curvature at the other of the upper and lower edges. This defines a partial truncated conic enclosed volume forward of the substantially planar rear wall, behind the curved translucent front face. The substantially planar rear wall has four side edges which form a trapezoid to which the translucent face is attached.
Another variation of the electroluminescent supplementary lighting device of the present invention is such that the translucent face has a configuration of a truncated pyramid, comprising a rectangular top surface and four side surfaces sloping downwardly therefrom.
In this embodiment, the substantially planar rear wall has four side edges to which the translucent face can be respectively attached.
The configuration is such that the truncated pyramid comprises a rectangular top surface and four side surfaces sloping downwardly therefrom, such that each of the side surfaces has a trapezoidal shape.
Each of side surfaces of the electroluminescent panel is separated from the adjacent ones of the side surfaces; and the top edges of each of the side surfaces are contiguous to and electrically connected with the rectangular top surface at the respective front and back electrically conductive layers of each.
Thus, the electroluminescent panel is disposed so as to nestle within the enclosed volume between the translucent face and the substantially planar rear wall, so that each of the side surfaces of the translucent face rests adjacent and above a corresponding one of the side surfaces of the electroluminescent panel.
In the truncated pyramid embodiment, of the electroluminescent supplementary lighting device of the present invention, one of the surfaces of each of the translucent front face and of the electroluminescent panel is square.
In any embodiment of the electroluminescent supplementary lighting device of the present invention, the connection to each of the front and back electrically conductive layers is made at the at least one side edge by connectors which are chosen from the group consisting of a pair of staples connected one to each of the respective electrically conductive layers, a pair of electrically conductive terminal pads secured one to each of the respective electrically conductive layers, and a pair of electrically conductive clips attached one to each of the respective electrically conductive layers.
In any connection according to the present invention, a pair of wires extends from the connectors into the enclosed volume through which an electrical connection is made between each of the connectors and a respective one of the electrical prongs.
Also, in any embodiment of the electroluminescent supplementary lighting device of the present invention, a connection tab may extend from the at least one side edge. In that case, the connection tab includes electrically conductive extensions of each of the front and back electrically conductive layers; and a pair of connection terminals extends away from the connection tab, one for each of the front and back electrically conductive layers, and is electrically insulated one from the other.
An electrical connection is made between each of the connection terminals and a respective one of the electrical prongs; and the connection tab is folded from the at least one side edge of the electroluminescent panel so as to extend there behind into the enclosed volume.
Still further, in any embodiment of the electroluminescent supplementary lighting device of the present invention, the size of the electroluminescent panel is such that the electroluminescent panel will fit snugly to the interior surface of the translucent front face.
Also. In any embodiment of the electroluminescent supplementary lighting device of the present invention, the side edges of the translucent face are attached to the side edges of the substantially planar rear wall by sealing means which are chosen from the group consisting of ultrasonic welding, mutually compatible solvents, adhesives, double-sided adhesive tapes, overlaid adhesive tapes, snapping adjacent edges together, and mixtures thereof.
Other embodiments of the present invention are as described above, except that the edges of the translucent front face do not terminate at the edges of the substantially planar rear wall, but they terminate at some intermediate position inwardly of the edges of the substantially planar rear wall but on the substantially planar rear wall.